In the medical field, medical professionals such as surgeons and dentists wear protective eyewear to provide protection against entry into the eye of bodily fluids or other potentially infectious or damaging substances from a patient. Surgeons and dentists, however, often also need to use magnification devices or other optical instruments whilst carrying out procedures on patients. To this end, the medical professional can wear normal glasses provided with an attachable pair of magnifying glasses. Such eyewear is commercially available from Swiss Medical Technology GmbH, Widnau, Switzerland. A modular eyewear system of this type including a pair of magnifying lenses is disclosed in WO 04/083941.
Besides the need for obtaining magnified views of objects of interest it is becoming more and more common for medical professionals to utilize three dimensional imaging. There are three main types of three dimensional imaging: stereoscopic, holographic, and multiplanar. Stereoscopic imaging uses various methods to convey a separate image to each eye, allowing the perception of depth. In order to perceive a three dimensional image, often stereoscopic monitors are viewed by means of special eyewear.
LCD shutter glasses, so-called active systems, are based on the property of a special form of glass containing a liquid crystal and a polarizing filter that becomes dark (i.e. opaque) when voltage is applied, but otherwise is translucent. A pair of eyeglasses made from such a material can be darkened over one eye, and then the other eye, in synchronization with the refresh rate of the stereoscopic monitor, while the stereoscopic monitor alternately displays different perspectives for each eye. At sufficiently high refresh rates, the viewer's visual system does not notice the flickering, each eye receives a different image, and the three dimensional effect is achieved. An exemplary electroscopic eyewear is disclosed in U.S. Pat. No. 6,388,797.
Polarized glasses create the illusion of three-dimensional images by restricting the light that reaches each eye. Two images are projected superimposed onto the same screen through orthogonal polarizing filters. The viewer wears eyeglasses which contain a pair of orthogonal polarizing filters. As each filter only passes light which is similarly polarized and blocks the orthogonally polarized light, each eye only sees one of the images, and the three dimensional effect is achieved.
The prior art devices have the disadvantage that a medical professional using eyewear including magnification devices and who also has the need to look at an operating area with higher magnification, e.g. with a stereoscopic microscope, has to switch to a different pair of glasses or has to remove the glasses each time he wants to look at a three dimensional image on a stereoscopic monitor or through a stereoscopic microscope.
The object of the present invention is to provide a device overcoming or at least mitigating the problem associated with the prior art devices.